1. Field of the Invention
The present invention relates to a television receiver and, more particularly, to a multi-screen high-definition television receiver for inserting current television signals in a high-definition screen and displaying a high-definition image and an image produced from the current television signals.
Digital integrated circuits have recently progressed in performance and, in particular, a memory whose access speed is high and manufacturing cost is low has been developed. The use of the memory enables digital processing of video signals. A television receiver having an image memory for carrying out functions of displaying still pictures and intermittently and slowly displaying pictures and a PIP (picture in picture) function of simultaneously displaying images on two screens, is commercialized.
The television market needs a high-definition television receiver having a large-sized screen. An EDTV (Extended Definition Television) for digitally processing television signals between frames or fields and converting interlaced scanning signals into sequential scanning signals, is developed to display current television signals with higher quality. The EDTV is disclosed in IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. COM-32, NO.8, AUGUST 1984, "Extended Definition TV Fully Compatible with Existing Standards" by Fikinuki et al.
On the other hand, a new type high-definition television receiver is going to be put into practice.
A high-definition television signal has 1125 scanning lines, interlace scanning of 2:1, a field frequency of 60.00 Hz, and an aspect ratio of 16:9. The high-definition television signal enables a wider screen and twice or more times as high definition in the longitudinal and lateral directions of the screen as the current television signal does. The current television signal has 525 scanning lines and whose interlace scanning is 2:1, field frequency is 59.94 Hz, and aspect ratio is 4:3. It is thus possible to enjoy TV programs with the real ambience. As the high-definition television receiver, a MUSE (Multiple Sub-Nyquist Sampling Encoding) system is used which is disclosed in INTERNATIONAL BROADCASTING SYMPOSIUM ON RADIO AND TELEVISION ENGINEERING, 1985, SESSION 2-(7), "Transmission of HDTV by MUSE system" by Yuichi N-NOMIYA et al.
When high-definition television receivers are commercialized in the near future under the condition mentioned above, the functions of the current television receivers, especially the PIP function will be certainly required in the high-definition television receivers.